1. Field of the Invention
This invention relates to an improved tensioner for an endless power transmission belt or the like, an improved part for such a tensioner or the like and to methods of making such a tensioner and/or part therefor.
2. Prior Art Statement
It is known to applicant to provide a tensioner for a power transmission belt that is adapted to be operated in an endless path, the tensioner comprising a support means for being fixed relative to the belt, a belt engaging means carried by the support means and being movable relative thereto, mchanical spring means operatively associated with the support means and the belt engaging means for urging the belt engaging means relative to the support means and against the belt with a force to tension the belt, and a fluid dampening means operatively associated with the support means and the belt engaging means to dampen the movement of the belt engaging means relative to the support means in at least one direction of movement thereof.
For example, see the copending patent application Ser. No. 296,694, filed Aug. 27, 1981 of Leslie B. Wilson, wherein the fluid dampening means comprises a cylinder means having a piston means therein and defining two chambers for fluid in the cylinder means on opposite sides of the piston means together with preferential flow control means interconnecting the two chambers together, and see the copending patent application Ser. No. 296,697, filed Aug. 27, 1981 of Randy C. Foster et al now U.S. Pat. No. 4,509,935 wherein the spring means is disposed in one of those chambers.
It is also known from the U.S. Pat. No. 2,514,139 to dispose a rotatable disc-like member in a fluid filled chamber to provide a vibration dampening means caused by the member creating a shear in the fluid as the member moves therein.
It is also known to provide a belt tensioner with a friction surface dampening means of the solid type utilized to tend to dampen vibrations and the like that are imposed on the belt tensioner.
It is also known to provide fluid couplings, such as torque converters, wherein rotational movement of one member causes rotational movement of another member because a fluid translates such movement between the two members, each member having vanes thereon.